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Irish Yobbo wrote: I came across the same problem when putting a lithium in my KZ. In normal operation the battery voltage was 14-14.5V - a little high for my liking, but OK. But when you turned the headlights on it would reach up to 15.5V at higher revs - just too much. Even when I cleaned the contacts it was still too high with the headlights on.

After cleaning all contacts and adding relays to the headlights, it's pretty stable now.

I went through the same overcharging when I found my brown wire voltage low. (regulator sense voltage) I went through all of the bullet connectors, soldered all of the connections at my fuse block (it did need attention) and even my ignition switch looking for the high resistance. Even after spending a day going over my wiring harness, I did not find the problem.

I also managed to break a plastic tab off of my ignition switch when I disassembled it to clean the contacts.



The cure is not to feed more power to the headlight, but to bring the sense voltage to proper levels. I added an ice-cube relay to bring the brown wire voltage to the proper levels. It has worked great ever since. Voltage levels are dead on. It starts and runs great every time since.

old_kaw wrote: The cure is not to feed more power to the headlight, but to bring the sense voltage to proper levels.

Well really, that's what I was doing by adding relays to the headlights. The regulator sense wire runs off the accessories circuit, so with the headlights on the voltage would drop on that circuit, which would raise the charging voltage. By taking the load off the accessories circuit there was no voltage drop, so it wouldn't overcharge.

Irish Yobbo wrote:

old_kaw wrote: The cure is not to feed more power to the headlight, but to bring the sense voltage to proper levels.

Well really, that's what I was doing by adding relays to the headlights. The regulator sense wire runs off the accessories circuit, so with the headlights on the voltage would drop on that circuit, which would raise the charging voltage. By taking the load off the accessories circuit there was no voltage drop, so it wouldn't overcharge.

I agree. By unloading the circuit the voltage should / would come up. I traced 3 accessory circuits through the ignition switch and my main concern was the charging system. There are indeed other switched accessories, and more voltage will certainly benefit them too, but since I have never experienced any problems with them. I used the brown sense wire to trigger the relay and fed it straight to the regulator.

In my opinion, it would be better to unload the circuit than to use the relay for a direct path from the battery to the regulator.

The relay introduces another set of contacts and relays do fail. If the relay fails when used as the only path for the regulator sense line, everything is going to start to smoke. Also, vibration has been known to make the relay contacts chatter in some mounting applications. That will wreak havoc with the sense line and would be very hard to diagnose because it will look exactly like a failing regulator.

I think a third option would be to use the relay as a direct line, but also give it a fail-safe bypass so if the relay fails, the regulator will still get a feed from the brown line albeit through a diode. All it really entails is adding a single 1 amp diode (1N4001 etc.). The voltage will still run high if the relay fails open. The diode will add a .7v drop to the original drop on the sense line, but at least the regulator output shouldn't be 20 to 25v, which is the risk without the diode.

But again, I should point out to others reading this, on a stock electrical system these are still short-cut solutions masking the real problem of contacts or wiring age. The solutions work and as long as you know you don't have significant drop elsewhere it's fine. It's definitely easier than re-wiring the whole bike.

Or does it stop charging if the switched wire voltage is removed? I have not tried this. I'll take my meter to the shed and can check this out easy enough later today.

I don't know if my voltage will come up if I unload the circuit, My headlight is always on and does not shut off. Frankly, this is working well and I am getting full B+ readings at the brown regulator wire. If it ain't broke, why "fix" it?

The chances of the relay failing is not as high as my starter or battery failing at a gas station. A 1n4001 diode has the usual diode voltage drop across the semiconductor junction of .7v, which would make the sense voltage even lower than it was before adding the relay. Either way it gets smoked. The way I found this problem in the first place was because I smelled wiring starting to burn after I replaced my stator. I was getting ready to put my helmet on and smelled something, I pulled the side cover and felt the soft and warm wiring.

EDIT: I just hooked my digital meter to the battery then pulled the 10 amp fuse to my relay, and the battery voltage spiked immediately to 16-18 volts with no voltage on the brown wire. It probably would have gone higher while frying everything and shorting the stator in the process. In conclusion to my testing, the relay shunt diode would be good insurance. I have some and will go add one now.



One of the most attractive things I find about the SH775 is the 5 wire design. The brown wire is not used to sense battery voltage. (BTW, my r/r is still the original OEM part)

I just added in a 1N4002 diode between terminals 85 and 87 on the relay.


This was the cleanest way to add one, without cutting wires.


I did see some interesting results. With the fuse pulled, battery voltages ran close to 16 volts @~ 3-4K rpm. But, nowhere near the excessive levels I witnessed with the sense voltage nonexistent. I'm sure it would have gone higher given longer duration / higher RPM's, but I am not feeling quite that frisky today. This is feeding the brown wire voltage through the 1N4002 diode with the 10 amp fuse pulled. Essentially this is the sense voltage less another .7 volt because of the diode. (good thing I am in between projects)


These are the voltages I see pretty consistently with my relay "band aid" in circuit furnishing full battery voltage to the regulator.


Voltage does hold pretty steady and RPM doesn't seem to make much difference on output levels, but then again, there is a lot of difference between sustained highway revs, and standing in my shed.

Great info guys, this is what these forums are really for.

Thanks for confirming the sense line operation and the diode patch. That's pretty impressive just a few hours later to have real-world results.

Yes, the diode will add another .7v drop (maybe less since that circuit uses very little current), but it's better than a total drop to zero volts, so it may buy you some time and/or some miles to make it back home. (And of course the diode doesn't hurt anything. It is inactive when the relay is functioning properly.)

A voltmeter would be a good early warning system to have... or even just a warning LED. I have a few simple projects you can build to make warning lights. I tried to keep them to the bare minimum parts.
s3.amazonaws.com/gpzweb/VoltMonitor/GPZ1LEDvoltMonitor.html
s3.amazonaws.com/gpzweb/VoltMonitor/GPZ3LEDvoltMonitor.html

Just to confirm your wiring:
Pin 86 is ground.
Pin 85 is switched 12v (originally brown wire).
Pin 30 is connected to the battery with a 10 amp fuse.
Pin 87 is to the brown wire of the regulator.
The diode is to 85 and 87

loudhvx wrote: Thanks for confirming the sense line operation and the diode patch.
That's pretty impressive just a few hours later to have real-world results.

Gee thanks my friend (s) . Rather than arguing with speculation, I should thank you. I am between projects right now. You know what they say about idle minds.

The diode is a little bit of insurance if the relay fails (not very likely). I couldn't believe how crazy the output voltages got within a few seconds after pulling the fuse with no sense voltage at all.

After all I already had the parts and my Weller soldering station is always sitting within reach.. It did take some digging however to find those diodes.

I do miss having a Radio Shack around. Sounds like you've spent some time there too.

I edited my earlier post with some other projects if you want to burn the dust off the old soldering iron.

loudhvx wrote: Just to confirm your wiring:
Pin 86 is ground.
Pin 85 is switched 12v (originally brown wire).
Pin 30 is connected to the battery with a 10 amp fuse.
Pin 87 is to the brown wire of the regulator.


The diode is to 85 and 87I do miss having a Radio Shack around. Sounds like you've spent some time there too.

I edited my earlier post with some other projects if you want to burn the dust off the old soldering iron.

That is exactly how it is hooked up. I didn't want to cut the connector off of my wiring harness so I made up a short jumper to hook the brown wire to my relay. The plug pin is still attached to the harness under the blue shrink.

I had the diodes already from a 30 amp 5 volt power supply I repaired for a CNC pipe bender at large cart and shelving manufacturer here. I worked industrial maint. for a automated equipment dealer sales and service co. for years.. I also was a flight simulator tech many moons ago. I loved the machines, the hours sucked. (3rd shift)

CNC pipe bender running Win XP:


A PC with XP and I/O interface cards. If you step on the mats, the machine stops.. Complicated machine, that will hurt you if you are stupid. Most machines will. The supervisor is checking it out to see if it's working. ::


At one time radio Shack had some neat stuff and lots of parts and kits. Towards the end, they were nothing much more than a high pressure cell phone pusher. I cringed at the thought of arguing with yet ANOTHER idiot trying to sell me a phone, yet he couldn't tell a diode from a hair dryer. Then when they filed bankruptcy, they sold off everyone's data that they mined.. Kinda like Zuckerburg selling your info.

For electronics repair parts in STL it's Gateway Electronics. I've known Them, and particularly Doug for many years ~20 i guess. When I was going to college getting my EE degree, I went to Gateway to buy components for the little assignment projects the instructors would require. They actually know what a diode is, and stock semiconductors and so much electronics junk it would make your head spin. It's kinda a mess, but Doug can point you towards whatever, or usually point you right to it. (as organized as electronics components can get) There are times I have to tell him not to quit his day job, but he takes it well. lol

www.gatewaycatalog.com/

I seem to remember that the brown voltage sense wire will only ramp up voltage if connected.
People who would boil batteries on old looms would disconnect it.